Much work has been directed to sealing of roll-on applicating packages. U.S. Pat. No. 2,823,403, which issued to R. H. Whitney on Feb. 18, 1958, for example, discloses an arrangement wherein a mechanical seal is provided between the lower portion of the dispensing ball and a fitment when the package closure is applied. A similar arrangement, but one in which a second seal is provided between the upper lip of the fitment and the dispensing ball, is disclosed in U.S. Pat. No. 4,164,377, which issued to R. D. Lohrman et al. on Aug. 14, 1979. In the latter patent, the screw closure sidewall has an inwardly extending integrally molded annular bead which is adapted to force the lip of the fitment radially inwardly, wedging it against the ball, to establish the upper mechanical seal.
Other techniques have also been taught as shown, for example, in U.S. Pat. No. 2,998,616, which issued to C. J. Gentile on Sept. 5, 1961, wherein a sealing member constructed of a resiliently deformable material (such as rubber or a resilient synthetic resin) is secured to the cap topwall and has a skirt adapted to form a mechanical seal with the ball and with a bearing surface on the fitment.
A roll-on applicator with a sharp sealing ring is described in U.S. Pat. No. 4,221,495, which issued to M. Braun et al. on Sept. 9, 1980. In this patent, a dispenser similar to that of the described Whitney patent is equipped with a fitment provided with a sealing ridge which is formed by a pair of angled, planar annular faces to establish sharp-line, fluidtight contact with the dispensing ball.
U.S. Pat. No. 3,090,987, which issued to H. S. Ruekberg on May 28, 1963, is directed to a package in which the ball socket is integrally molded with the container to obviate the need of assembling a fitment on a container neck and of assuring a seal therebetween. Ruekberg also describes alternative embodiments in which single and double mechanical seals of the type described above are provided.
A further dual-seal, roll-on dispensing package is taught in U.S. Pat. No. 4,168,128, which issued to W. E. Fillmore et al. on Sept. 18, 1979. In this roller-type package the application of the closure forces the roller into contact with the bottom diaphram of the socket, thus establishing a lower seal. In addition, the closure has a quantity of resilient sealing material therein which is positioned to engage the upper surface of the roller and the lip of the fitment to provide a second seal when the closure is applied. The resilient sealing material can comprise foamed polymers, such as polyethylene foam or polyurethane foam, which are light in weight and effective as a sealing material. As a consequence, each of the seals is essentially of the mechanical type.
Despite all of the good work done, there remains a problem in sealing roll-on applicating dispensing packages when the product to be dispensed contains liquid components having very low surface tensions. For example, with antiperspirant compositions containing volative and/or nonvolatile silicone constituents it is extremely difficult, if not impossible, to economically provide a mechanical seal or seals which will uniformly and without fail prevent migration of such constituents. These silicones have surface tensions in the range of from about 18 to about 21 dynes/cm.sup.2 at 25.degree. C. and it has been found that at least trace amounts thereof will penetrate the seals of an unacceptable percentage of existing types of roll-on packages. The silicones spread to the outer surfaces of the containers and caps causing them to be unsightly and unpleasant to handle, a severe commercial detriment to a manufacturer.
It is an object of this invention to obviate the abovedescribed problems.
It is another object of the present invention to provide a roll-on dispensing package which economically provides protection against migration of fugitive liquids to external package surfaces to improve the visual and tactile impressions of the package.